Shape sensing with inverse finite element method for slender structures

Pierclaudio Savino,Marco Gherlone,Francesco Tondolo 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.72 No.2

The methodology known as "shape sensing" allows the reconstruction of the displacement field of a structure starting from strain measurements, with considerable implications for structural monitoring, as well as for the control and implementation of smart structures. An approach to shape sensing is based on the inverse Finite Element Method (iFEM) that uses a variational principle enforcing a least-squares compatibility between measured and analytical strain measures. The structural response is reconstructed without the knowledge of the mechanical properties and load conditions but based only on the relationship between displacements and strains. In order to efficiently apply iFEM to the most common structural typologies of civil engineering, its formulation according to the kinematical assumptions of the Bernoulli-Euler theory is presented. Two beam inverse finite elements are formulated for different loading conditions. Depending on the type of element, the relationship between the minimum number of required measurement stations and the interpolation order is defined. Several examples representing common applications of civil engineering and involving beams and frames are presented. To simulate the experimental strain data at the station points and to verify the accuracy of the displacements obtained with the iFEM shape sensing procedure, a direct FEM analysis of the considered structures is performed using the LUSAS software.

BRAND DEVOTED VS. NOT BRAND DEVOTED: DIFFERENCE IN CONSUMER PREFERENCES

Antonio Iazzi,Savino Santovito 글로벌지식마케팅경영학회 2015 Global Fashion Management Conference Vol.2015 No.06

In the process that leads to the purchase of a product, the consumer, guided by the reasons for which he or she has decided to make the purchase (motivation), seeks information that will be useful in making the best choice, minimising the associated risks (Erdem &Swait, 1998). The literature (Kotler 2003) refers mainly to consumer behaviours founded on rational principles. Indeed, the product is understood as the sum of a number of attributes that enable it to meet the needs that prompted the purchase in the first place. Depending on the weight attributed to each attribute (Fishbein 1967), different market segments are generated, reflecting different consumer behaviours. It therefore becomes indispensable for companies to understand how each potential consumer evaluates a product’s attributes and what role is played in this regard by the brand. Although the behaviour of consumers cannot easily be schematised, given the specific characteristics of each individual, it can be argued that the process of choosing a product depends on the consumer’s preference for either branded or unbranded goods (Hasan et al. 2012, Mohtar & Abbas 2014). The expectations that have developed in the consumer with respect to a brand, with the awareness of the characteristics that it is able to provide, can modify the perception of the attributes and thus the preferences that arise from the evaluation process. The literature confirms the existence of a positive relationship between the brand and the perception of quality that can increase trust in it (Krishnan et al., 1989; Ubilava et al. 2011). For this reason, the objective of the study is to assess the perception of a product’s attributes by two categories of consumers: brand-oriented and non-brand-oriented. The work thus concerns the choice of positioning strategies, which vary precisely in relation to the existence or otherwise of a brand. This was conducted with reference to the Jeans sector, given both its intrinsic characteristics (variety of production, orientation to differentiation, growth in consumption) and the frequent and specific attention paid to it by the managerial literature dealing with consumer purchasing processes (among others, see: Lee, 1990; Park & Lee, 1999; Delong et al.,2002; Vrontis & Vrontis, 2004; Wu, 2005; Wu & Delong, 2006; Jin et al., 2010). The above-mentioned objectives were pursued in accordance with a mixed-method research approach, divided into the following steps: a) an on-desk survey of the managerial literature on the sector in question and an in-depth qualitative investigation (by means of the so-called “laddering” interview technique), both aimed at identifying the purchase attributes of the jeans product; b) compilation of a questionnaire (with a pilot test conducted on 20 consumers) by 600 consumers (non-probabilistic sample) who regularly buy jeans. The data was processed by descriptive and multivariate statistical techniques (using SPSS software) in order to assess the role of the various purchase attributes with reference to the two types of consumer identified. As previously mentioned, the first on-field method of analysis used was of the in-depth, qualitative type (Russell et al. 2004; Philips & Reynolds 2009; Orsingher et al., 2011). It entailed 80 interviews (40 for each of the two categories of consumer, brand-devoted and non-brand-devoted, the number being useful for the goals to pursue as indicated by Reynolds et al., 2001), with the objective of highlighting and analysing the terminal values to which the individual aspires. To this end, we used the so-called “laddering” interview technique, which makes it possible to identify both the content of the three variables being analysed and the causal relations between them. The variables are (Reynolds & Gutman, 1988): the attributes (tangible and intangible), the consequences (functional and psychological benefits) and the values (instrumental and terminal). Specifically the “hard laddering” technique (Botschen & Hemetsberger, 1998) was used, which guides the respondent towards increasingly higher levels of abstraction. The “paper-and-pencil” method was applied, which made it possible to minimise the respondents’ conditioning, allowing them to follow their own cognitive route (Grunert, 1995). The interpretation of the information acquired by these methods made it possible to observe and understand the deep and personal motives that determine the choice of jeans product (see, among others, Orsingher et al. 2011; Fu & Wu, 2013), and thus to gain a more direct and effective understanding of the consumer’s behaviour. Once the attributes that determine the purchase of a pair jeans had been identified, the next step was the creation of the questionnaire with which to perform the sample-based investigation, conducted on 600 consumers1 who regularly purchase jeans. 55% of the sample interviewed were Italian, purchasing 1 to 4 pairs of jeans a year. Specifically, 31% of the sample purchased the product once every three months, while a further 32% purchased it twice a year. 78% were between 18 and 35 years old, while 2 out of 3 were women. With regard to the objectives of the present work, 33% purchased unbranded jeans while 67% were brand-devoted consumers. For measurement of the analysis variables, a normal assessment scale (1 = lowest value; 5 = highest value) was used. Specifically, the SPSS software was used to process the data so as to identify (by means of regression analysis) any correlation between the choice variables. For each of the two categories of consumer a factorial analysis was performed in order to identify factors that were shared by the measured determinants of choice, followed by a cluster analysis. This made it possible to: (a) identify the different role in the consumer choice process of the attributes and the other dimensions of analysis (benefits and values); (b) verify the presence of any differences in the role that the choice variables play in the purchase process among the two different categories of consumer being analysed; and (c) identify any clusters of consumers within each profile (brand-devoted and non-brand-devoted). The main objective was to verify the perception of the product choice variables by the two categories of consumer observed. This consideration is highly important to the choice of communication strategy, for both companies interested in the growth of their Brand Identity and unbranded companies. For the latter, it is the store, particularly the sales personnel, that plays the key role in the purchaser’s choices. It is in this context that non-brand-devoted consumers, verifying the characteristics of the product and its potential benefits, make their choice in consideration of the “desired final state” (values) that that they seek to obtain. In addition, the identification of clusters may enable, for the sector in question, a greater knowledge of the consumer and thus the activation of segmentation strategies and relative competitive positioning.

Non-linear aero-elastic response of a multi-layer TPS

Pasolini, P.,Dowell, E.H.,Rosa, S. De,Franco, F.,Savino, R. Techno-Press 2017 Advances in aircraft and spacecraft science Vol.4 No.4

The aim of the present work is to present a computational study of the non-linear aero-elastic behavior of a multi-layered Thermal Protection System (TPS). The severity of atmospheric re-entry conditions is due to the combination of high temperatures, high pressures and high velocities, and thus the aero-elastic behavior of flexible structures can be difficult to assess. In order to validate the specific computational model and the overall strategy for structural and aerodynamics analyses of flexible structures, the simplified TPS sample tested in the 8' High Temperature Tunnel (HTT) at NASA LaRC has been selected as a baseline for the validation of the present work. The von $K{\acute{a}}rm{\acute{a}}n^{\prime}s$ three dimensional large deflection theory for the structure and a hybrid Raleigh-Ritz-Galerkin approach, combined with the first order Piston Theory to describe the aerodynamic flow, have been used to derive the equations of motion. The paper shows that a good description of the physical behavior of the fabric is possible with the proposed approach. The model is further applied to investigate structural and aero-elastic influence of the number of the layers and the stitching pattern.